Copolymers of styrene, dimethyl itaconate and acrylonitrile and a process for their manufacture



N 1964' MESSINA ETAL 3,156,741

COPOLYMERS OF STYRENE, ETHYL ITACONATE AND ACRYLOMITRILE A PROCESS F THEIR MANUFACTURE ed Nov. 17, 1959 III United States Patent This invention relates to copolyrners and to a process for making the same.

The copolymers according to the invention are broadly characterized in that they are the copolymerization products of a styrene-dimethyl itaconate mixture, wherein the styrene is present in amounts ranging from 30 to 90 percent by weight, and preferably from 55 to 77 percent, while methyl itaconate is present in amounts ranging from 70 to 10 percent by weight, and preferably from 45 to 23 percent. The optimum ratio is: styrene 62.5 percent/dimethyl itaconate 37.5 percent.

According to a particular form of the invention, the copolymers are the copolymerization products of the aforesaid mixture together with acrylonitrile, this latter being present in an amount from 1 to 30 percent, and

preferably, from 5 to percent, calculated on the overall weight of monomers. All parts and percentages in tlus specification are by weight.

It is known that both styrene and dimethyl itaconate can be separately polymerized. Styrene gives a transparent polymer with good chemical and electric properties, which has found many practical applications. However, it is somewhat brittle and its mechanical properties are not very good. On the other hand, dimethyl itaconate gives a very brittle and friable polymer. Thus,

the fact that the copolymers of styrene and dimethyl A itaconate defined above have properties superior to those of polystyrene from the view point of mechanical strength and reduced brittleness is wholly unexpected and surprising; In addition, said copolymers are more transparent than polystyrene itself.

The extrusion and injection-molding of said copolymers can be accomplished more easily than even those of polystyrene.

The ternary copolymers obtained from styrene, dimethyl itaconate and acrylonitrile have further surprising advantages.

They are characterized mainly by very good resistance to solvents of the benzene type. Thus, for instance, while a binary copolymer, when tested for resistance to a mixture of gasoline with percent of benzene, quickly becomes opaque, the ternary copotymer is not attacked by said mixture and remains clear and transparent.

Moreover, an improvement'in a number of mechanical properties is obtained, such as in the impact bending strength, and resistance to traction, bending and compression.

The process according to the invention for making said copolymers is broadly characterized in that the monomermixture in the stated proportions isblock polymerized by a period from about 24 hours to a few days, at tem- 3,156,741 Patented Nov. 10, 1964 ice benzoyl peroxides, azodiisobutyronitrile, tertiary butyl permaleinate, cyclohexanone peroxide, and methylethylke tone hydroperoxide.

When copolymerizing styrene-dimethyl itaconate-acrylom'trile mixtures, it is preferred to adopt a temperature diagram which will be defined hereinafter by graphical means.

According to a preferred form of the invention an amount of previously prepared copolymer is added to the mixture of monomers before polymerization. Said amount is in the range of 2 to 20 percent and preferably 3 to 10 percent of the overall Weight of the mixture of monomers and added polymer. This addition does not alter the process in any other way, but has many advantageous effects.

First of all, the polymerization time is materially decreased, and is practically halved, all other conditions being equal to obtain a copolymer of the same relative viscosity.

Further, the volatile matter content of the polymer is also materially decreased. Such a decrease is very important, since gas pockets are formed by such volatile matter when the polymer is processed, thereby impairing the transparency of the finished products and lowering their mechanical properties. By operating according to said particular form of the invention, the volatile matter content can be reduced, for instance, from} to 4 percent (as obtained when the monomer mixture only is copolymerized) to 2 to 2.5 percent. Moreover, the volatile matter content can be further reduced to 0.5 to 1 percent by effecting the polymerization in the preferred range of 60-90 C. and subsequently heating the product for a few hours at a temperature higher than C.

Finally, the copolymers obtained by the polymerization of a mixture of monomers containing a previously pre pared copolymer have better mechanical-physical properties, as will be seen hereafter.

The invention will be better understood from the following examples.

EXAMPLE 1 EXAMPLE 2 375 parts of dimethyl itaconate are mixed with 625 parts of styrene, commercial grade, and 2.25 parts of lauryl peroxide are then added. The resulting mixture is poured into a suitable container, which is then dipped into a water bath thermostatically controlled at 70 C. After four days, a copolymer with the same properties of that resulting from Example 1 is obtained.

EXAMPLE 3 The polymerization is .carried out as in Example 1, using the same amounts of monomers, except that no catalyst is added. The Water bath temperature is C. The mixture is left in said water bath for two days. After'this time, acopolymer with M.P. 125 -l35" peratures in the range of 60-l50 C, and preferably of:

60-90 C, preferably in the presence of catalysts, such as organic peroxides or hydroperoxides in amounts ranglag between about 0.05 and 1 percent. The lauryl-, or

benzoyl-peroxides are the most suitable for said purpose;

Other possible catalysts are, for instance: the chloro- C. and relative viscosity 1.5 is obtained.

EXAMPLE 4 The. polymerization is carried out as in Example 1, but 230 parts by weight of dimethyl itaconate and 770 parts by weight of commercial grade styrene are used.

A copolymer with Ml. l60165 C. and relative viscosity 2.9 is obtained.

A The preparation of ternary copolymers from styrene, dilnethyl itaconate and acrylonitrile is illustrated in Examples 9 and 10, with reference to the attached diagram EXAMPLE 5 and in Table II. The polymerization is carried out as in Example 1, 5 EXAMPLE 9 but 450 parts by weight of dlmethyl ltaconate and 550 arts b wei ht of commercial rade st rene are used. g conosllrmrawith MP C relative A monomer mixture consisting of 40 kg. of d methyl obta. itaconate, 55 leg. of styrene and kg. of acrylonltrlie (for cosly is me 0 instance with a 5 percent addition of acrylonitrile) is EXAMPLE 6 taken as starting material. 500 g. of lauryl peroxide (0.5 percent calculated on the weight of mixture) are The polymerization is Carried out as in Example 1, added to said mixture and after dissolution of catalyst, but 550 Parts by Wight of dimethyl itaconate and 450 the mixture 18 transferred into sultable containers, which parts by weight of commercial grade styrene are used. are then dipped into a thermostatically controlled water A copolymei. with MR C. and relative bath. In this example the polymerlzatlon dlagram ls as cosity of 2.2 is obtained. follows:

EXAMPLE 7 36 hours of heating at 50 C. 20 12 hours of heating at 60 C. The polymerization is carried out as in Example 1, 24 hours of heating at 70 C. buttflitl partslltay Yeight of diinethyll itaconate and 30d0 24 hours of heating at C. par 5 y welgi o commercla gra e styrene are use c o O A copolymer with MP. 150155 C. and relative vis- I hours heanng at 110 and 120 cosit of 1.8 is obtained. 25

y A transparent, pale-yellow colored polymer 1S obtalned.

EXAMPLE 8 EXAMPLE 10 The polymerization is carried out as in Example 1 but 100 parts by weight of dimethyl itaconate and 906 A fixture of 30 of dlrpeihyl f 60 5 of parts by wei ht of styrene, commercial grade, are used. styrene and 10 f flcliylommle instance W 10 A coqolymeg with M D 165o 170o C and relative percent of acrylonltrile) 1S taken as starting material and cos; 3 is Obmnad 1 kg. (1 percent) of lauryl peroxide is dissolved therein. The Surprising pliopertics of the copolymers Obtained The resulting mixture is subdivided into suitable conare shown in Table I, wherein the properties of a copolyminers? 3 processed according to a temperature. (hamer obtained from 62 5 percent of Styrene and 37 5 Pep gram similar to that of Example 1. A transparent, slightly cent of dimethyl itaconate are compared with those of ysnow comma X i a standard polystyrene The polymerization diagram of the previous example is given only as an example. Any other temperature Table I 40 diagram, included between the broken lines (I) and (II) in the attached diagram, and preferably falling within copolvmcr standard the hatched area defined by the broken lines (III) and according to polystyrene (IV) might be selected. Said area is open to the right, theml'cmm since an additional heating of the order of hours is not A substantially harmful in general. itiifi irf'ie lihas;rsrnanti::::: sit; 1&3?) 111 e the hours) are marked on Compressive strength, ASTM D695, kg./ 830 m the absclssae, while the temperatures (in C.) are marked s .en 1 n 'leiisile strength, ASIM D638 435 290 on the ordmi'ms- Bending strength, ASfIM DZ 0 840 95 Table II shows the properties of a copolymer made 92 88 according to Example 9 and a copolymer made accord- Rel nv viscosity g3 percent solution in 2 2 2 8 3 2 ing to Example 10 compared to those of a binary copolygifigg gggg e gfi9 '1: am 1754550 mer (37.5 percent of dimethyl itaconate and 62.5 per Refractive index, ASTM D542 1- 56 cent of styrene).

The methods employed are stated in Table II.

Table II Ternary Ternary Binary Method Unit copolymer copolymer copolynler Example 9 Example 10 Relative viscosity (0.5% concentration)" Dirncthylformamide solu 1. 32 1. 40 1. 25

Melting index O. 10 O. 11 0.2 Heat distortion temperature (66 p.s.i.) 97 95 n5 Vicat softening point 107 107 92 Specific weight 1.14 1.122 1.14 Reiraetiveindex 1. 54 1. 535 1. 559 'lransparence 84 82 85 Rockwell hardness 85 85 Breaking elongation 2. 06 1. G 1. 40 Modulus of elasticity 33, 000 32, 500 35, 000 Tensile strength ASTM D638 Kg./sq.c1n 655 630 Bending strcngth ASIM D790" Kg./sq.cm 1,010 1,020 840 Compressive strength ASTM D695 Kgi/s'qfiImnn 890 955 830 :g. 0111. Impact bending strength Izod, with }ASTM D256 2.58 2. 61 1.8

notch. cm. of notch The process according to a practical form of the invention, hereinbefore referred to, is illustrated in Example 11 and Table III. 1

i 2 EXAMPLE ll 6. in the range of from about 60' to 150 C. for a period of time of at least about 24 hours.

2. A process as claimed in claim 1 wherein said copolymerization is conducted in the presence of a catalyst 71 of dimethyl itaconate are mixed with 119 kg 5 selected from the group consisting of benzoyl peroxide of styrene, kg. of a copolymer previously made as lzxryl peroxlde'l d 1 1 described herein, are dissolved in said hot monomer miX- .process as c alme m 6 81m comprising a mg ture. The copolymer to be added might also be made relatlvely i 5 of i copolymenc pioduct by the copolymerization of a monomer mixture without of the polymenzanon of a ltmxwre Styren? 1n the the addition of polymer. The resulting mixture consists 10 ilmount of 30 to 90 parts by Welght and ethyl ltaconzite therefore of 35.5 percent of dimethyl itaconate, 59.5 peri f f farts by welght to the cent of styrene and 5 percent of the polymer. 200 g. T ylene an f fi (for instance of benzoyl peroxide are added thereto.- h 2 33 as i i m compnsmg rst Such mixture, after having been poured into suitable con- Ea mg 0 e mix f at temperatures m the miners is heated to C for 48 hours range of 60 to 90 C. for 24 L0 96 hours and a second This,already yields a copolymer with g properties. heating thereafter at temperatures in the range of 100 To obtain a further decrease in the volatile matter conto 1 for 3 to p g' 1 3 h h tent, the already polymerized mass is further heated at Process as alme c mm W erem Sal 1l0120 C. for 12 hours. Changes might be made in polymimc product 18 prlesent the amount of 2 E 20% the abovestated times and temperatures. Thus, the polym- 20 b wglght of the resulmig mlxture of styrene dlmethyl erization time may last from 24 to 96 hours instead ltaconateaild copolymenc product of 48 hours, and the temperatures can be between 60 A F iansparent copolyme? obtamqd by and 90 C. The second treatment might be performed polymenzmg mlxiure of i i dimethyl ltaconate at temperatures in the range of 0 C and for and acrylonitrile, said acrylonitrile being present in the times ramming from 3 to 24 hours 25 amount of l to by weight of styrene and dimethyl Table in Shows the properties of a copolymer itaconate and the remainder of said mixture being contained according to Example 11 compared with those of a Smuted by 30 P Paris g of i and 70 to copolymer obtained by polymerizing the same monomer 10 hafts by wiflgnt dlmethyl ltaconae, Said p y mixture, with the same catalyst, without any addition no f g a Ineltlng P t Of at l ast about 125 C. and a of previously made polymer, for a time of 4 days at o VISCOSliy Of I10 m t a a ut -3- 70 C. The methods employed are stated in the table. 7. A copolymer as claimed in claim 6 Where-in said Table III Polymer Binary 00- Method Unit obtained polymer of according to Table II Example 11 Relative viscosity (0.5% concen- Dimethylforrnanide solu- 1. 29 1.25

tration) tion. Melting index ASTM D1238 0.11 0. 2 I fieat distortion temperature (66 ASTM D648 C 103 95 Vicat softening point 113 92 Specific weight 1. 14 1. 14 Refractive index 1. 56 1. 559 Transparenee (spectrophotometer)- 85 85 Rockwell hardness 88 85 Ultimate tensile strength 585 435 Ultimate elongatioml. 66 1. Modulus oi elasticity KgJsq. cm 31, 000 35, 000 Bending strength KgJsq. cm 950 840 Compressive strength ASTM D695 Kg./sq em.. 935 830 1 tb din t e th g arrwtrnossii 2252 0m,

The polmerizat-ion can always be carried out using another peroxide, specially lauryl peroxide, in place of benzoyl peroxide, or vice versa, and the amount of catalyst is always in the stated range of about 005 1 percent,

but benzoyl peroxide is preferably used in amounts close to 0.05-1 percent, while lauryl peroxide is employed in somewhat larger amounts suchas 0.2-1 percent. When no catalyst is used, higher temperatures or larger times are required.

While a number of examples have been given, these are not limitative as many changes and adaptations may be made therein by persons skilled in the art without itaconate and heating the resulting mixture at temperatures acrylonitrile is present inthe amount of 5 to 10% by weight of styrene and dimethyl itaconite.

8. A process for copolymerizing styrene and dimethyl itaconate comprising mixing styrene in the amount of 30 to parts by weight, dimethyl itaconate in the amount of 70 to 10 parts by weight and acrylonitrile in the amount of l to 30% by weight of styrene and dimethyl itaconate and heating the resulting mixture in the presence of a peroxide catalyst between about 40 to 90 C. for about 72 hours and then between about 60 to C. for at least 48 hours.

9. A process as claimed in claim 8 wherein said resulting mixture is heated between about 40 to 70 C. for about 24 hours, then between about 40 to 90 C. for about 36 hours, then between about 50 to 90 C. for about 12 hours, then between 60 to 120 C. for about 24 hours and finally between about 80 to 120 for at least 12 hours.

10. A resinous terpolymer of acrylonitrile, styrene and dimethyl itaconate.

(References on following page) UNITED STATES PATENTS Voss et a1 July 14, 1936 DAlelio Apr. 14, 1942 5 Coffman et a1 Dec. 25, 1945 Gilbert Oct. 18, 1949 Schertz Nov. 13, 1951 8 Barrett Apr. 13, 1954 Banes et a1 Nov. 20, 1956 Slocombe et a1 Apr. 1, 1958 Weiss May 31, 1960 Ketterer Mar. 7, 1961 FOREIGN PATENTS Canada June 2, 1959 

1. A PROCESS FOR COPOLYMERIZING STYRENE AND DIMETHYL ITACONITE COMPRISING MIXING STYRENE IN THE AMOUNT OF 30 TO 90 PARTS BY WEIGHT AND DIMETHYL ITACONATE IN THE AMOUNT OF 70 TO 10 PARTS BY WEIGHT AND ACRYLONITRILE IN THE AMOUNT OF 1 TO 30% BY WEIGHT OF STYRENE AND DIMETHYL ITACONATE AND HEATING THE RESULTING MIXTURE AT TEMPERATURES IN THE RANGE OF FROM ABOUT 60 TO 150*C. FOR A PERIOD OF TIME OF AT LEAST ABOUT 24 HOURS.
 10. A RESINOUS TERPOLYMER OF ACRYLONITRILE, STYRENE AND DIMETHYL ITACONATE. 